domingo, 20 de mayo de 2012

Did Our Solar System evolve in a Separate, More Oxygen-Rich Part of the Milky Way?

Based on new data from NASA’s IBEX spacecraft this past January, which is able to sample material flowing into the solar system from interstellar space, scientists "Detected alien matter that came into our solar system from other parts of the galaxy--and, chemically speaking, it’s not exactly like what we find here at home.” according to David McComas the principal investigator for IBEX at the Southwest Research Institute in San Antonio, Texas.

“There are at least two possibilities," says McComas. "Either the solar system evolved in a separate, more oxygen-rich part of the galaxy than where we currently reside or a great deal of critical, life-giving oxygen lies trapped in interstellar dust grains or ices, unable to move freely throughout space—and thus undetectable by IBEX."

Either way, this affects scientific models of how our solar system – and life – formed.“It’s a real puzzle,” he says.

Using data from IBEX, the researchers team compared the neon-to-oxygen ratio inside vs. outside the heliosphere, they reported that for every 20 neon atoms in the galactic wind, there are 74 oxygen atoms. In our own solar system, however, for every 20 neon atoms there are 111 oxygen atoms, which means there's more oxygen in any given slice of the solar system than in local interstellar space.

Launched in 2008, the IBEX spacecraft spins in Earth orbit scanning the entire sky, detecting neutral alien atoms that slip through the heliosphere’s magnetic defenses. Without actually exiting the solar system, IBEX is able to sample the Milky Way outside.

"We've directly measured four separate types of atoms from interstellar space and the composition just doesn't match up with what we see in the solar system," said Eric Christian, mission scientist for IBEX at NASA's Goddard Space Flight Center.

Among the four types of atoms detected—H, He, O and Ne—the last one, neon, serves as a particularly useful reference. “Neon is a noble gas, so it doesn’t react with anything. And it’s relatively abundant, so we can measure it with good statistics,” explains McComas.